# Pendulum Problem: Why Has It Stopped Oscillating?

• apchemstudent
In summary, the conversation discusses the concept of a pendulum and how it oscillates due to tension in the rope. However, when the entire system is in freefall, there is no longer tension in the rope and the pendulum stops oscillating. This is similar to holding a pendulum up and letting go, with no centripetal force to keep it in motion. The conversation also mentions the possibility of the bob being at its highest kinetic energy and what would happen to its horizontal speed in this scenario. The conversation ends with a clarification that the question was simply about whether the pendulum would continue to oscillate or not, regardless of its horizontal speed.
apchemstudent
The answer to the attachment is that the pendulum has stopped oscillating. Why is this? Please explain this thoroughly to me, i would be very grateful of it. Thanks...

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The reason the pendulum oscillates is that there is tension in the rope holding it to the ceiling. The ball on the pendulum has potential energy and due to the tension in the rope will follow a pendulum path, however when the elevator falls, the entire system is freefall. There is no longer tension in the rope, because the entire system is falling at the same speed.

This is equivalent to holding a pendulum up, swinging it, and just letting go. Once there is no more tension in the rope, there is no centripetal force to keep it in motion.

Suppose the bob was at its point of highest kinetic energy when the cable broke. What will happens to the horizontal speed of the bob?

I'm really curious about this. Why does the bob stop? What happens to its horizontal speed?

quasar987 said:
I'm really curious about this. Why does the bob stop? What happens to its horizontal speed?

I think the question was only looking for whether it will still oscillate or not. So even though there might be a horizontal component of the velocity, it had stopped oscillating.

## 1. Why is my pendulum not oscillating anymore?

There could be several reasons for this. One possible reason is that the pendulum may have lost energy due to friction or air resistance. Another reason could be that the pendulum's length has changed, altering its natural frequency. Additionally, the pendulum may have been disturbed by external forces, such as vibrations or movement of the support structure.

## 2. How can I get my pendulum to start oscillating again?

If the pendulum has lost energy, you can add more energy to it by giving it a gentle push or by raising its point of suspension. If the length of the pendulum has changed, you can adjust it back to its original length. If external forces have caused the pendulum to stop, try moving it to a more stable location with less vibration.

## 3. Can a pendulum stop oscillating on its own?

Yes, a pendulum can eventually stop oscillating due to the effects of friction and air resistance. As the pendulum swings back and forth, it encounters resistance from the air and from the pivot point. Over time, this resistance can cause the pendulum to lose energy and eventually stop oscillating.

## 4. How does the length of a pendulum affect its oscillation?

The length of a pendulum directly affects its oscillation because it determines the pendulum's natural frequency. The longer the pendulum, the slower its natural frequency, meaning it will take longer to complete one full swing. Similarly, a shorter pendulum will have a faster natural frequency and complete more swings in a given time.

## 5. Is there a limit to how long a pendulum can oscillate?

In theory, a pendulum can oscillate indefinitely as long as there is no external interference and the pendulum is receiving a small amount of energy with each swing to compensate for the energy lost due to friction and air resistance. However, in reality, a pendulum will eventually stop due to these factors, as well as other environmental factors that can affect its motion.

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